Liquid-crystalline polymer molding

ABSTRACT

The present invention is to provide a liquid crystal polymer molded article which has an excellent low warpage and is able to be suitably used particularly as a connector or the like. That is, a molded article of a liquid crystal composition in which 100 parts by weight of a liquid crystal polymer (A) and 5-100 parts by weight of a non-fibrous filler (B) are compounded where the non-fibrous filler is so dispersed that, when a diffraction peak of the non-fibrous filler is measured by a transmission method and a reflection method by means of a wide-angle X-ray diffraction, the diffraction peak of the non-fibrous filler which can be confirmed by the reflection method is not confirmed by the transmission method.

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention concerns a molded article using a liquidcrystal polymer composition blended with a non-fibrous filler and,optionally, a fibrous filler. More in particular, it relates to a liquidcrystal polymer composition of excellent less warping property which isparticularly suitable for a connector and the like requiring low warpafter molding and during reflow heating.

PRIOR ART

[0002] A liquid crystal polymer capable of forming an anisotropic moltenphase has been known among thermoplastic resins, as a material excellentin dimensional accuracy and damping property and generating extremelylittle flash during molding. Heretofore, taking advantage of suchfeatures, liquid crystal polymer compositions reinforced with glassfibers have generally been adopted as SMT coping connectors. However,since connectors have been reduced in weight, thickness and size inrecent years, existent molded articles using reinforcing materials onlyconsisting of glass fibers cause a problem that they are deformed uponreflow to result in soldering failure with substrates due toinsufficient rigidity because of the insufficient thickness, theanisotropy of glass fibers and internal stresses caused by pressure uponmolding. Further, molded articles, using a reinforcing material onlyconsisting of non-fibrous fillers or a composite filler reinforcingmaterial comprising a non-fibrous filler and a glass fiber, can suppressdeformation upon reflow but involves a problem of fracture upon fittingdue to insufficient strength of the molded article per se. Thus, moldedarticles capable of overcoming all of the problems described above havenot yet been present.

DISCLOSURE OF THE INVENTION

[0003] In view of the foregoing problems, the present inventors havemade earnest research and study on materials having excellentcharacteristics regarding less warping property and mechanicalproperties and accomplished the invention based on the finding that theless warping property can be obtained without greatly deteriorating themechanical properties by using a material in which a non-fibrous filleris blended in a specific amount into a liquid crystal polymer andmolding the same so as to provide a particular oriented state.

[0004] That is, this invention provides a molded article of a liquidcrystal polymer composition in which 100 parts by weight of a liquidcrystal polymer (A) is blended with 5 to 100 parts by weight of anon-fibrous filler (B) in which a non-fibrous filler is so dispersedthat when a diffraction peak of the non-fibrous filler is measured by areflection method and a transmission method by means of a wide-angleX-ray diffraction, the diffraction peak of the non-fibrous filler thatcan be recognized by the reflection method can not be confirmed by thetransmission method.

DETAILED DESCRIPTION OF THE INVENTION

[0005] The present invention is to be explained specifically. The liquidcrystalline polymer (A) used in the invention means a melt processablepolymer capable of forming an optically anisotropic molten phase. Theproperty of the anisotropic molten phase can be recognized by anordinary polarization inspection method utilizing crossed polarizers.More specifically, the anisotropic molten phase can be confirmed byusing a Leitz polarization microscope and observing a molten specimenplaced on a Leits hot stage at a 40× magnification ratio in a nitrogenatmosphere. The liquid crystal polymer applicable to this inventionusually permeates a polarized light even in a molten stationary state toexhibit optical anisotropy when inspected between crossed polarizers.

[0006] The liquid crystal polymer (A) described above has no particularrestriction but is preferably an aromatic polyester or an aromaticpolyester amide and also includes those polyesters containing anaromatic polyester or aromatic polyester amide partially in onemolecular chain. Those having a inherent viscosity (I. V.) of,preferably, at least about 2.0 dl/g and, further preferably, 2.0 to 10.0dl/g when dissolved at a concentration of 0.1% by weight inpentafluorophenol at 60° C. are used.

[0007] The aromatic polyester or aromatic polyester amide as the liquidcrystal polymer (A) employable to this invention is, particularlypreferably, an aromatic polyester or aromatic polyester amide having, asthe constituent, at least one compound selected from the groupconsisting of aromatic hydroxycarboxylic acids, aromatic hydroxyaminesand aromatic diamines.

[0008] More specifically, they include,

[0009] (1) polyester mainly comprising at least one of aromatichydroxycarboxylic acids and derivatives thereof;

[0010] (2) a polyester mainly comprising (a) at least one of aromatichydroxycarboxylic acids and derivatives thereof, (b) at least one ofaromatic dicarboxylic acids, alicyclic dicarboxylic acids andderivatives thereof, (c) at least one of aromatic diols, alicyclicdiols, aliphatic diols and derivatives thereof;

[0011] (3) polyester amides mainly comprising (a) at least one ofaromatic hydroxycarboxylic acids and derivatives thereof, (b) at leastone of aromatic hydroxyamine, aromatic diamine and derivatives thereof,and (c) at least one of aromatic dicarboxylic acids, alicyclicdicarboxylic acids and derivatives thereof; and

[0012] (4) polyester amide mainly comprising (a) at least one ofaromatic hydroxycarboxylic acids and derivatives thereof, (b) at leastone of aromatic hydroxyamines, aromatic diamines and derivativesthereof, (c) at least one of aromatic dicarboxylic acids, alicyclicdicarboxylic acids and derivatives thereof, and (d) at least one ofaromatic diols, alicyclic diols, aliphatic diols and derivativesthereof. Further, a molecular weight controller may optionally be usedtogether with the constituents described above.

[0013] Preferred examples of the specific compounds constituting theliquid crystal polymer (A) applicable to this invention can includearomatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and6-hydroxy-2-naphthoic acid, aromatic diols such as2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene,4,4′-dihydroxybiphenyl, hydroquinone, resorcin and compounds representedby the following formulas (I) and (II); and aromatic dicarboxylic acidssuch as terephthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylicacid, 2,6-naphthalene dicarboxylic acids and compounds represented bythe following formula (III); and aromatic amines such as p-aminophenol,and p-phenylene diamine.

[0014] The particularly preferred liquid crystal polymer (A) applied tothis invention is an aromatic polyester amidecomprising-hydroxybenzoicacid, 6-hydroxy-2-naphthoicacid, terephthalicacid and p-aminophenol as the main constituent unit component.

[0015] For attaining the less warping property as an object of theinvention, it is necessary that 5 to 100 part by weight of a non-fibrousfiller (B) has to be dispersed based on 100 parts by weight of theliquid crystal polymer (A) so that when a diffraction peak of thenon-fibrous filler is measured by a transmission method and a reflectionmethod by means of a wide-angle X-ray diffraction, the diffraction peakof the non-fibrous filler confirmed by the reflection method is notconfirmed by the transmission method. Even if the non-fibrous filler isused, when a molded article is measured by the reflection method and thetransmission method by means of the wide-angle X-ray diffractiometry andthe diffraction peak of the non-fibrous filler is confirmed also by thetransmission method, the non-fibrous filler is not dispersed so as toexhibit the less warping property. For dispersing the non-fibrous fillerso that the diffraction peak thereof is no more confirmed by thetransmission method, the injection speed during molding is important. Ifthe injection speed is too slow, the non-fibrous filler is not in such adispersion state that the diffraction peak by the transmission methodcan not be confirmed. On the other hand, if it is too fast, since itforms an uneven layer by the resin jetting, the dispersion state isunfavorably worsened. Accordingly, the injection speed is preferably 100to 400 m/sec, preferably, 150 to 300 mm/sec.

[0016] The non-fibrous filler (B) used in the invention is a spherical,indefinite, tetrapot-shaped or plate-shaped filler not having extensionin one specified direction like fibrous fillers and, particularly, aplate-like filler such as of disk-like, square, rectangular orindefinite plate shape, particularly having extension in two directionsand having no extension in the remaining one direction tend to bedispersed as described above and is used preferably.

[0017] Such a non-fibrous filler and a plate-like filler comprisesmaterials, for example, talc, mica, kaolin, clay, graphite, vermiculite,silicates such as calcium silicate, aluminum silicate, feldspar powder,acidic white clay, agalmatolite clay, sericite, sillimanite, bentonite,slate powder and silane, carbonates such as calcium carbonate, chalk,barium carbonate, magnesium carbonate and dolomite, sulfates such asballite powder, branc fixe, precipitation calcium sulfate, calcinedgypsum, and barium sulfate, hydroxides such as alumina hydrate, oxidessuch as alumina, antimony oxide, magnesia, titanium oxide, zinc powder,silica, siliceous sand, quartz, white carbon and diatomaceous earth,sulfides such as molybdenum disulfide and metallic particles.

[0018] Among them, talc, mica, kaolin and graphite are preferred in viewof the performance.

[0019] For attaining the less warping property, the more content of thenon-fibrous filler, the better. But excessive addition worsens theextrudability and moldability, particularly, flowability and, further,lowers the mechanical strength.

[0020] Further, the less warping property can not be developed also whenthe addition amount is too small. Accordingly, the content of thenon-fibrous filler (B) is from 5 to 100 parts by weight, preferably, 10to 50 parts by weight based on 100 parts by weight of the liquid crystalpolymer (A).

[0021] For improving the mechanical properties, a fibrous filler (C)with an average fiber diameter of 5 to 20 μm and an average aspect ratioof at least 15 may further be incorporated.

[0022] As the fibrous filler (C), glass fiber, carbon milled fiber,fibrous wollastonite, whisker, metallic fiber, inorganic fiber andmineral fiber can be used. For the carbon milled fiber, a PAN fiberusing polyacrylonitrile as the raw material and a pitch fiber usingpitch as the raw material is used.

[0023] As the whisker, silicon nitride whisker, silicon trinitridewhisker, basic magnesium sulfate whisker, barium titanate whisker,silicon carbide whisker and boron whisker are used.

[0024] As the metallic fiber, fibers of soft steel, stainless steel,steel and alloys thereof, brass, aluminum and alloys thereof and leadare used.

[0025] As the inorganic fiber, various fibers of rock wool, zirconia,alumina silica, potassium titanate, barium titanate, titanium oxide,silicon carbide, alumina, silica and blast furnace slag are used.

[0026] As the mineral fiber, asbestos and the like are used.

[0027] Among them, glass fiber is preferred in view of the performance.As the glass fiber, ordinary glass fibers as well as glass fibers coatedwith metals such as nickel and copper, or silane fibers can be used.

[0028] Referring to the addition amount of the fibrous filler forimproving the mechanical properties, the extrudability and themoldability, particularly, the flowability is worsened when the additionamount is large, whereas mechanical strength is lowered when theaddition amount is small. Accordingly, the content of the fibrous filler(C) is 5 to 100 parts by weight, preferably, 10 to 50 parts by weightbased on 100 parts by weight of the liquid crystal polymer (A).

[0029] In this case, the non-fibrous filler (B) serves to improve theless warping property but the excessive content thereof worsens theextrudability and moldability to make the material fragile. The fibrousfiller (C) serves to improve the mechanical property but the excessivecontent thereof increases the deformation upon reflow. Accordingly, thetotal content of the components (B) and (C) has to be 150 parts byweight or less, preferably, 100 parts by weight or less based on 100parts by weight of the liquid crystal polymer (A).

[0030] The non-fibrous filler and the fibrous filler used in theinvention can be used as they are but a known surface treating agent anda known binder used generally may be used together.

[0031] Further, a composition provided with desired properties by theaddition of additives such as nucleating agent, pigment such as carbonblack, antioxidant, stabilizer, plasticizer, lubricant, mold releasingagent and flame retardant are also included within the scope of theliquid crystal polymer composition defined in the invention.

[0032] In the liquid crystal polymer molded article according to thepresent invention, when a liquid crystal polymer composition blendedwith at least one of non-fibrous fillers and, optionally, at least oneof fibrous fillers are used, the non-fibrous filler is dispersed duringmolding to obtain a molded article of excellent less warping propertywithout deteriorating the mechanical property and, further, higherperformance can be provided in a state where each of the fillers isuniformly dispersed in the molded article with the non-fibrous fillerbeing present between the fibrous fillers.

[0033] For producing such a liquid crystal polymer composition, both ofthem may be incorporated at the compositional ratio described above andextruded. Usually, they are extruded in an extruder into pellets andthen used for injection molding but there is no restriction to theproduction by such extruders.

[0034] Further, the method of molding by using the liquid crystalpolymer composition described above includes injection molding,extrusion molding or blow molding, with no particular restriction onlyto such methods.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035]FIG. 1 is a drawing showing a shape of a connector type test pieceused in the examples in which (a) is a front elevational view, (b) is abottom view and (c) is a cross sectional view taken along line A-A in(A).

[0036]FIG. 2 is a measurement chart showing the result of measuringdiffraction peaks of the non-fibrous filler by a reflection method bymeans of wide-angle X-ray diffractiometry in a molded article of Example3.

[0037]FIG. 3 is a measurement chart showing the result of measuringdiffraction peaks of the non-fibrous filler by a transmission method bymeans of wide-angle X-ray diffractiometry in a molded article of Example3.

[0038]FIG. 4 is a measurement chart showing the result of measuringdiffraction peaks of the non-fibrous filler by a reflection method bymeans of wide-angle X-ray diffractiometry in a molded article ofComparative Example 5.

[0039]FIG. 5 is a measurement chart showing the result of measuringdiffraction peaks of the non-fibrous filler by a transmission method bymeans of wide-angle X-ray diffractiometry in a molded article ofComparative Example 5.

EXAMPLES

[0040] The present invention is to be explained specifically by way ofexamples but it is not restricted to them. Measurement and examinationof physical properties in the examples were conducted by the followingmethod.

[0041] (1) Measurement of Plate Flatness

[0042] A flatplate of 60×60×0.7 mm was fixed at three points on a levelplate (platen) and a height of a position where the flat plate waslifted most from the surface of the platen was measured to determine anaverage for three flat plates.

[0043] (2) Measurement of Warp of a Connector

[0044] In a connector type test piece with an inter terminal pitch of0.6 mm, an average wall thickness (t) of the product of 0.3 mm, anexternal size of the product of 4 mm width×4 mm height×60 mm length andrecessed as shown in FIG. 1, a distance between a line joining points onboth ends of the connector fixing surface and a point at the centralpart was measured and average for ten connectors was determined.

[0045] (3) Measurement of Dispersion of the Non-fibrous Filler in aMolded Article

[0046] In a connector-shaped molded article, a portion to be measuredwas cut out and used for a wide-angle X-ray diffraction. The test piecewas measured by the reflection method and the transmission method toconfirm the absence or presence of the diffraction peaks of thenon-fibrous filler. As typical examples, the measurement charts ofExample 3 are shown in FIGS. 2 and 3 and the measurement charts ofComparative Example 5 are shown in FIGS. 4 and 5.

Examples 1 to 7 and Comparative Examples 1 to 6

[0047] To 100 parts by weight of a liquid crystal polyester (LCP: VECTRAE950i, manufactured by Polyplastics Co., Ltd.), each of the fillersshown in Table 1 was dry blended at a ratio shown in Table 1. Themixture was melt-extruded and pelletized by a twin-screw extruder (ModelPCM-30, manufactured by Ikegai Tekko Co., Ltd.). When the test specimenswere manufactured from the pellets by an injection molding machine at aninjection speed shown in Table 1 and evaluated, the result shown inTable 1 was obtained. Each of the fillers used is as below.

[0048] Talc: Crown talc PP, manufactured by Matsumura Sangyo

[0049] Fine powder talc: HS-T0.5, manufactured by Hayasi Kasei Co.,

[0050] Mica: REPCOMICA M325CE, manufactured by Repco, Inc.

[0051] Koalin: HYDRITE FLAT D, manufactured by Dry Branch Kaolin

[0052] Graphite: HAG-15, manufactured by Nippon Kokuen

[0053] Wollastonite: NYAD325, manufactured by NYCO

[0054] Spherical silica: FB-74, manufactured by Denki Kagaku Kogyo

[0055] Titanium oxide: SR1, manufactured by Sakai Chemical

[0056] GF: glass fibers, chopped strand of 10 μm fiber diameter, 3 mmfiber length TABLE 1 Measurement results of (A) LCP Filler Pate flatnessWarp of connector X-ray diffraction (parts (parts by weight) InjectionWarping Injection Warping By Reflection By Transmission by (B) (C) speedamount speed amount method method weight Non-fibrous Fibrous (mm/sec)(mm) (mm/sec) (mm) Peaks of Filler Ex. 1 100 Talc 150 0.12 200 0.269presence absence 50 Com. 100 GF 150 0.89 200 0.545 absence absence Ex. 150 Ex. 2 100 Talc GF 150 0.10 200 0.230 presence absence 60 20 Ex. 3 100Talc GF 150 0.07 200 0.230 presence absence 20 30 Com. 100 Talc GF 330.91 83 0.320 presence presence Ex. 2 20 30 Com. 100 Talc GF 450 1.25450 0.431 presence presence Ex. 3 20 30 Ex. 4 100 Fine powder GF 1500.18 200 0.220 presence absence 100 talc 30 20 Ex. 5 100 Mica GF 1500.20 200 0.272 presence absence 100 20 30 Ex. 6 100 Kaolin GF 150 0.25200 0.270 presence absence 100 20 30 Com. 100 Graphite GF 150 0.35 2000.285 presence absence Ex. 7 20 30 Com. 100 Wollastonite GF 150 0.95 2000.319 presence present Ex. 4 20 30 Com. 100 Spherical GF 150 12.13 2000.360 presence present Ex. 5 silica 30 20 Com. 100 Titanium GF 150 4.42200 0.471 presence Ex. 6 oxide 30 20

1. A molded article of a liquid crystal polymer composition in which 100parts by weight of a liquid crystal polymer (A) and 5-100 parts byweight of a non-fibrous filler (B) are compounded where the non-fibrousfiller is so dispersed that, when a diffraction peak of the non-fibrousfiller is measured by a transmission method and a reflection method bymeans of a wide-angle X-ray diffraction, the diffraction peak of thenon-fibrous filler which can be confirmed by the reflection method isnot confirmed by the transmission method.
 2. The molded articleaccording to claim 1, wherein the non-fibrous filler (B) is aplate-shaped filler.
 3. The molded article according to claim 2, whereinthe plate-shaped filler comprises at least one member selected fromtalc, mica, kaolin and graphite.
 4. The molded article according to anyone of claims 1 to 3, wherein a liquid crystal polymer composition where5-100 parts by weight of a fibrous filler (C) having an average fiberdiameter of 5-20 μm and an average aspect ratio of not less than 15 isfurther compounded to 100 parts by weight of the liquid crystal polymer(A) is used.
 5. The molded article according to claim 4, wherein thefibrous filer (C) comprises glass fiber.
 6. The molded article accordingto any one of claims 1 to 5, wherein a liquid crystal polymercomposition where the liquid crystal polymer (A) is polyester amide isused.
 7. The molded article according to any one of claims 1 to 6,wherein the molded article is a connector.